1. Field of the Invention
The present invention relates to a substrate processing apparatus and method for subjecting a substrate to processing such as ion-implantation, film deposition accompanied by ion-implantation and plasma processing, and more particularly to simplify an apparatus configuration and improving the throughput thereof.
2. Description of the Related Art
FIG. 10 is a plan view showing an exemplary conventional substrate processing apparatus. This substrate processing apparatus is an ion doping apparatus (ion implanter without mass separation referred to also in the following description) having a total of four vacuum chambers of a processing chamber 8, a transfer robot chamber 16 and two spare vacuum chambers 14. Reference numerals 20 to 22 denote vacuum valves.
The processing chamber 8 serves to a substrate (e.g. a substrate for liquid-crystal display or a semiconductor substrate referred to also in the following description). Within the processing chamber 8, a holder 4 for holding the substrate 2 is provided. An ion source 10 is attached to the wall thereof. The substrate 2 on the holder 4 is irradiated with ion beams 12 so that it is subjected to the processing such as ion implantation. The holder 4 is rotated between an upright condition for substrate processing and a horizontal condition for substrate replacement by a holder driving mechanism 6.
The transfer robot chamber 16 serves to house a transfer robot 18 for transferring the substrate 2 in vacuum. The transfer robot 18 is a robot equipped with two or three shafts, which has an arm 19 for placing the substrate 2 thereon to replace a processed substrate and a non-processed substrate with each other for the holder in the horizontal condition within the processing chamber 8 and transfer-out/in of the substrate 2 for both spare chambers 14.
Each spare vacuum chamber 14 serves to transfer the substrate 2 between an atmosphere and the environments of vacuum. In the air in front of the spare chamber 14, a three-shaft transfer robot 24 is provided to have an arm 25 to transfer the substrate 2 placed thereon in and out from each spare vacuum chamber 14.
An explanation will be given of the overall operation of the substrate processing apparatus. A non-processed substrate 2 is transferred into the processing chamber along a path indicated by arrow a-c in FIG. 10. The non-processed substrate 2 is irradiated with the ion beams 12 so that it is subjected to the processing such as ion implantation. The processed substrate 2 is transferred into the environment of air along the path indicated by arrow d-f. In this way, substrates 2 will be processed-one by one.
The substrate processing apparatus has four vessels (i.e., processing chamber 8, transfer robot chamber 16 and two spare chambers 14). In addition, these vacuum vessel must be evacuated respectively to vacuum. This makes the apparatus configuration complicate.
Further, the arm-type transfer robot 18 equipped with two or three shafts is used for substrate transfer in vacuum. Such a transfer robot 18 is complicate in configuration and expensive. This also makes the apparatus configuration complicate.
Using the spare vacuum chambers 14 (and the transfer robots 24 on the side of air) unified into a single spare chamber, the substrates before and after the processing can be loaded or unloaded in order one by one between the vacuum and air. However, such a configuration makes the time required for load/unload of the substrate 2 longer by the degree of reduction of one spare chamber 14, thereby attenuating the throughput (processing capability of the substrate 2 per unit time). In this case also, three vacuum vessels must be still provided.
If the number of vacuum vessels can be reduced into two of the processing chamber 8 and spare vacuum chamber 14, the apparatus configuration can be simplified remarkably.
However, because of such a simple configuration, the transfer robot 18 has to be housed within the spare chamber 14. In such a configuration, there-are disadvantages that (1) the transfer robot 18 occupies a fairly large volume so that the spare vacuum chamber 14 has to be formed to have a large volume, and that (2) the transfer robot 18 has a complicate structure to make it difficult the environment to be evacuated to vacuum. Because of these two causes, the evacuation speed in the auxiliary vacuum chamber 14 is reduced to lower the throughput of the apparatus. Further, reduction of the spare vacuum chambers into a single chamber lowers the throughput as described above. Accordingly, the throughput of the apparatus will be lowered fairly.